// MIT License

// Copyright (c) 2019 Erin Catto

// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:

// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.

// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.

#include "test.h"

/// This is a test of typical character collision scenarios. This does not
/// show how you should implement a character in your application.
/// Instead this is used to test smooth collision on edge chains.

class CharacterCollision : public Test
{
public:
  CharacterCollision()
  {
    // Ground body
    {
      b2BodyDef bd;
      b2Body* ground = m_world->CreateBody(&bd);

      b2EdgeShape shape;
      shape.SetTwoSided(b2Vec2(-20.0f, 0.0f), b2Vec2(20.0f, 0.0f));
      ground->CreateFixture(&shape, 0.0f);
    }

    // Collinear edges with no adjacency information.
    // This shows the problematic case where a box shape can hit
    // an internal vertex.
    {
      b2BodyDef bd;
      b2Body* ground = m_world->CreateBody(&bd);

      b2EdgeShape shape;
      shape.SetTwoSided(b2Vec2(-8.0f, 1.0f), b2Vec2(-6.0f, 1.0f));
      ground->CreateFixture(&shape, 0.0f);
      shape.SetTwoSided(b2Vec2(-6.0f, 1.0f), b2Vec2(-4.0f, 1.0f));
      ground->CreateFixture(&shape, 0.0f);
      shape.SetTwoSided(b2Vec2(-4.0f, 1.0f), b2Vec2(-2.0f, 1.0f));
      ground->CreateFixture(&shape, 0.0f);
    }

    // Chain shape
    {
      b2BodyDef bd;
      bd.angle = 0.25f * b2_pi;
      b2Body* ground = m_world->CreateBody(&bd);

      b2Vec2 vs[4];
      vs[0].Set(5.0f, 7.0f);
      vs[1].Set(6.0f, 8.0f);
      vs[2].Set(7.0f, 8.0f);
      vs[3].Set(8.0f, 7.0f);
      b2CreateLoop(ground, vs, 4);
    }

    // Square tiles. This shows that adjacency shapes may
    // have non-smooth collision. There is no solution
    // to this problem.
    {
      b2BodyDef bd;
      b2Body* ground = m_world->CreateBody(&bd);

      b2PolygonShape shape;
      shape.SetAsBox(1.0f, 1.0f, b2Vec2(4.0f, 3.0f), 0.0f);
      ground->CreateFixture(&shape, 0.0f);
      shape.SetAsBox(1.0f, 1.0f, b2Vec2(6.0f, 3.0f), 0.0f);
      ground->CreateFixture(&shape, 0.0f);
      shape.SetAsBox(1.0f, 1.0f, b2Vec2(8.0f, 3.0f), 0.0f);
      ground->CreateFixture(&shape, 0.0f);
    }

    // Square made from an edge loop. Collision should be smooth.
    {
      b2BodyDef bd;
      b2Body* ground = m_world->CreateBody(&bd);

      b2Vec2 vs[4];
      vs[0].Set(-1.0f, 3.0f);
      vs[1].Set(1.0f, 3.0f);
      vs[2].Set(1.0f, 5.0f);
      vs[3].Set(-1.0f, 5.0f);
      b2CreateLoop(ground, vs, 4);
    }

    // Edge loop. Collision should be smooth.
    {
      b2BodyDef bd;
      bd.position.Set(-10.0f, 4.0f);
      b2Body* ground = m_world->CreateBody(&bd);

      b2Vec2 vs[10];
      vs[0].Set(0.0f, 0.0f);
      vs[1].Set(6.0f, 0.0f);
      vs[2].Set(6.0f, 2.0f);
      vs[3].Set(4.0f, 1.0f);
      vs[4].Set(2.0f, 2.0f);
      vs[5].Set(0.0f, 2.0f);
      vs[6].Set(-2.0f, 2.0f);
      vs[7].Set(-4.0f, 3.0f);
      vs[8].Set(-6.0f, 2.0f);
      vs[9].Set(-6.0f, 0.0f);
      b2CreateLoop(ground, vs, 10);
    }

    // Square character 1
    {
      b2BodyDef bd;
      bd.position.Set(-3.0f, 8.0f);
      bd.type = b2_dynamicBody;
      bd.fixedRotation = true;
      bd.allowSleep = false;

      b2Body* body = m_world->CreateBody(&bd);

      b2PolygonShape shape;
      shape.SetAsBox(0.5f, 0.5f);

      b2FixtureDef fd;
      fd.shape = &shape;
      fd.density = 20.0f;
      body->CreateFixture(&fd);
    }

    // Square character 2
    {
      b2BodyDef bd;
      bd.position.Set(-5.0f, 5.0f);
      bd.type = b2_dynamicBody;
      bd.fixedRotation = true;
      bd.allowSleep = false;

      b2Body* body = m_world->CreateBody(&bd);

      b2PolygonShape shape;
      shape.SetAsBox(0.25f, 0.25f);

      b2FixtureDef fd;
      fd.shape = &shape;
      fd.density = 20.0f;
      body->CreateFixture(&fd);
    }

    // Hexagon character
    {
      b2BodyDef bd;
      bd.position.Set(-5.0f, 8.0f);
      bd.type = b2_dynamicBody;
      bd.fixedRotation = true;
      bd.allowSleep = false;

      b2Body* body = m_world->CreateBody(&bd);

      float angle = 0.0f;
      float delta = b2_pi / 3.0f;
      b2Vec2 vertices[6];
      for (int32 i = 0; i < 6; ++i)
      {
        vertices[i].Set(0.5f * cosf(angle), 0.5f * sinf(angle));
        angle += delta;
      }

      b2PolygonShape shape;
      shape.Set(vertices, 6);

      b2FixtureDef fd;
      fd.shape = &shape;
      fd.density = 20.0f;
      body->CreateFixture(&fd);
    }

    // Circle character
    {
      b2BodyDef bd;
      bd.position.Set(3.0f, 5.0f);
      bd.type = b2_dynamicBody;
      bd.fixedRotation = true;
      bd.allowSleep = false;

      b2Body* body = m_world->CreateBody(&bd);

      b2CircleShape shape;
      shape.m_radius = 0.5f;

      b2FixtureDef fd;
      fd.shape = &shape;
      fd.density = 20.0f;
      body->CreateFixture(&fd);
    }

    // Circle character
    {
      b2BodyDef bd;
      bd.position.Set(-7.0f, 6.0f);
      bd.type = b2_dynamicBody;
      bd.allowSleep = false;

      m_character = m_world->CreateBody(&bd);

      b2CircleShape shape;
      shape.m_radius = 0.25f;

      b2FixtureDef fd;
      fd.shape = &shape;
      fd.density = 20.0f;
      fd.friction = 1.0f;
      m_character->CreateFixture(&fd);
    }
  }

  void Step(Settings& settings) override
  {
    b2Vec2 v = m_character->GetLinearVelocity();
    v.x = -5.0f;
    m_character->SetLinearVelocity(v);

    Test::Step(settings);
    g_debugDraw.DrawString(5, m_textLine, "This tests various character collision shapes.");
    m_textLine += m_textIncrement;
    g_debugDraw.DrawString(5, m_textLine, "Limitation: square and hexagon can snag on aligned boxes.");
    m_textLine += m_textIncrement;
    g_debugDraw.DrawString(5, m_textLine, "Feature: edge chains have smooth collision inside and out.");
    m_textLine += m_textIncrement;
  }

  static Test* Create()
  {
    return new CharacterCollision;
  }

  b2Body* m_character;
};

static int testIndex = RegisterTest("Examples", "Character Collision", CharacterCollision::Create);
